Embolization in selected regions of the body is becoming of increasing therapeutic importance in treating conditions such as arteriovascular malformations, aneurysms, fistulas, vascular tumors, and the like. In some instances, the procedure involves placing foreign bodies such as metal coils, balloons, beads, and the like into the vessel. For example, vaso-occlusion devices are surgical implements or implants that are placed within the vasculature of the human body, typically via a catheter, either to block the flow of blood through a vessel making up that portion of the vasculature through the formation of an embolus or to form such an embolus within an aneurysm stemming from the vessel. One widely used vaso-occlusive device is a helical wire coil having windings which may be dimensioned to engage the walls of the vessels. (See, e.g., U.S. Pat. No. 4,994,069 to Ritchart et al.) Other less stiff helically coiled devices have been described, as well as those involving woven braids.
U.S. Pat. No. 5,354,295 and its parent, U.S. Pat. No. 5,122,136, both to Guglielmi et al., describe an electrolytically detachable embolic device. Vaso-occlusive coils having little or no inherent secondary shape have also been described. For instance, co-owned U.S. Pat. Nos. 5,690,666 and 5,826,587 by Berenstein et al., describes coils having little or no shape after introduction into the vascular space.
At times these bodies become errant or it is desired to retrieve and remove them from the vessel for other reasons. However, existing snares are sometimes too stiff or too large to permit deep tissue access through tortuous vessel paths. For instance, U.S. Pat. No. 5,098,440 is directed to a method and device for retrieving or repositioning a stent within a blood vessel. The apparatus includes a distal end with a loop for engaging the stent, a proximal end for manipulating the distal end and an intermediate portion that is shielded from the blood vessel by an elongated catheter.
PCT/US93/00875, filed Feb. 2, 1993, incorporated by reference in its entirety, is directed to a medical retrieval device with catheter and guidewire components. The distal end of the guidewire is coil-wrapped and forms a loop which is affixed to the distal end of the catheter. The size of the loop is altered by axial movement of the proximal portion of the guidewire.
Various configurations have been used to remove calculi from the biliary or urinary system. See, for instance, U.S. Pat. No. 5,064,428. Additionally, devices having various configurations have been used to remove objects from the vasculature. For example, surgical devices comprising one or more expandable and collapsible baskets have been described for removing or piercing a thrombus in the vasculature. See, U.S. Pat. Nos. 6,066,149. 5,868,754 describes a three prong-shaped device for capturing and removing bodies or articles from within a vessel.
None of the above documents show a device as described herein which includes a stop element to help keep the retriever element in the desired position.